Friday, September 06, 2013

September sizzler! Winnipeg records hottest September day in 30 years. Cooler weather for the weekend with showers by Monday..

3 pm temperatures across southern MBSept 6 2013

It was a September sizzler as the remnants of a very warm airmass from western Canada pushed over southern Manitoba today sending temperatures into the low 30s this afternoon, with humidex values peaking around the 40 mark.. almost unheard of for September. In Winnipeg, temperatures peaked at 33.8C at YWG airport, making it the hottest September day in the city in 30 years since a 38.8C reading on Sept 2 1983. A weak cold front pushing south from the interlake was producing some widely scattered thunderstorms late today, and a severe thunderstorm watch was issued for much of southern MB including Winnipeg and the Red River valley. Not everyone will see storms this evening due to their isolated nature, but the potential is there for some of these storms to become severe with strong wind gusts and large hail as the main threats.

This front will usher in cooler and less humid air for the weekend with sunshine and 25C temperatures for Saturday.. a fine looking start to the weekend. Clouds will be spreading in on Sunday as a disturbance tracks across the northern Plain states, which will likely bring some showers and embedded thunderstorms over southern MB including the Red River valley Sunday night into Monday. This could be the most significant rainfall in Winnipeg since a thunderstorm brought 30 mm of rain to the city back on August 18th. Since then, rain has been scarce with only 2 mm falling in Winnipeg over the past 3 weeks.

18 comments:

I know we've had other days just as hot as today this summer, but for some reason today just *feels* hotter. I don't know if it's maybe that the cooler temps lately have made me less used to it or what, but today is indeed a sizzler!

Ready for a good soaking. Getting sick and tired of these 3 week+ dry outs happening on a regular basis and, adding constant disappointment with all this promising heat/humidity yet storms refusing to produce which is like (and I’ve said this before) the absentee father that promises to show up, only to dash your hopes and doesn’t show up. Shaping up to be another disappointing end to a disappointing year. Sure hope next year is better after a colossal fail for the last 3 summers. IMO, this is not a normal pattern we’re in. Look at the soaking rains interior BC and Southern Alberta have been getting over normally semi arid landscapes. The triggers/jet stream have just not been lining up for us while a lot of the other stuff has. Luckily, our climate is extreme enough that it can change at any point and completely reverse, not sticking to any particular pattern. Whether you like the pattern we’re in or not, just wait a while and it will probably change. Unfortunately we’ve been waiting 3 years now...

Area of weakening showers will be spreading east into Winnipeg/RRV Sunday, with some showers possible by midday or so and lingering into the afternoon or just gradually dissipating. Models then blow up another batch of convection over North Dakota late tomorrow through Sunday night into Monday and track heaviest activity over northern ND and along US border into SE MB. If this scenario pans out, then Winnipeg probably won't see much rain over the next couple of days as the heaviest activity tracks to our south and east. We'll see if the convection tomorrow night sets up further north.. but the way this year is going, I wouldn't count on it.

Now I know why they established the border right there, to separate the rain from no rain. Funny how the weather often seems to be literally completely different close to or just on the other side of it. I've lost count of how many times I've seen everything happen just along or south of it! This year though has been especially bad for that it seems. Winnipeg though it seems, is just out of reach of a better storm tracking location, which seems to get better the more south you go (and sometimes north too). South is better for frontal and jet stream setups for triggers it seems, and the north is better for topographic triggers like the hills to the west or the lakes. Putting all that together, we literally are in a dead zone when it comes to storms :(. Time to move!

I see the data for these dates is missing on the climate online site.. not sure why. The data is there. If you know how to read synoptic messages, you can get the actual synoptic report from the OGIMET site at..

>> Anonymous said... With that being said, models do show 40mm of precip falling over us by tomorrow. Think that could happen? Or is that "overdone" like it always is?

Last night's model runs have shifted the convective complex that blows up tonight north into southern MB, with significant precip amounts noted of 50-75 mm! We'll see if this trend is maintained with today's model runs.. but it could be an interesting night over southern MB.

Newest model runs this morning have shifted axis of heaviest rain back south again tonight into Monday, mainly over northern ND into northern MN with spillover into southern RRV and SE MB. Models still show measurable precip into Winnipeg, about 5-15 mm overnight into Monday, but bulk of heaviest rain (25-75 mm) will likely be just south of intl border. Given expected evolution of surface low and upper features, this scenario seems more reasonable than a further north solution.

The latest 1981-2010 normals show that the 30 year September average has risen 0.4C from 1971-2000 normals (12.7C vs 12.3C). So indeed, this past decade has seen warmer Septembers than the past. But this fits the overall trend of warmer falls and later starts to winter over the past decade or so. November average is now 0.4C warmer than a decade ago (-4.9C vs -5.3C), and December is over a degree warmer (-13.2C vs -14.4C) Given the considerable loss of Arctic sea ice over the past decade, it makes sense that our falls would be warmer and winters starting later, as it's taking longer for Arctic air to intensify over the far north before trekking south. Of course, not every year is like this, and some years can have earlier starts to winter (such as last year) but overall, there has definitely been a trend to later starts to winter over the past decade, and less severe winters overall. That's not to say we can never have a severe winter here (it's southern MB after all!), it's just that the frequency is less than in the past.

That OGIMET site is quite interesting Rob, thanks. I'm not too sure how to read the synoptic messages, however I've read some descriptions about how to read it on EC's website and I think I might understand.

I notice that the data is missing again on Sep 1, 4 and 5 on EC's site again so I just looked at those synoptic messages and might have found the data... can you verify to see if I got it correct please?Sep 1 high 19.5°C and low 7.1°CSep 4 high 21.7°C and low 2.7°CSep 5 high 28.8°C and low 8.8°CCorrect me if I'm wrong... eventually I will learn this so I can find the data without begging you for it.

Yes, those figures you came up with are exactly right! You're a quick learner!

For the benefit of others.. in the synoptic message, the 0600Z message will show the day's final high, low and 24hr precip to one decimal point after the '333' group. The 10xxx group is the day's high (the "0" will be a "1" for negative temps), the 20XXX group is the day's low, and the 70XXX group is the 24hr precip.

In the above string, "71852" is the syno number for YWG airport, and the values after the 333 group show the day's high, low and precip. "10235" denotes a high of +23.5C, "20122" is a low of +12.2C, and 70000 means 0.0 mm of precip today.

Given the number of missing data these days on EC's climate website, this is a handy way of keeping track of the daily figures.

That may have been residual precip from the rain event the day before. It's possible that 6.0 mm fell on the 10th, but the gauge only recorded 3.0 mm that day, with the other 3.0 mm registering on the 11th. Sometimes these automated gauges lag the event by a few hours.

I know this is off topic but I thought I'd report THE SMELL here in addition to 311 & councillor Grant Nordman, but there is a very heavy smell of sewage or maybe even a pig farm in the Westwood area this morning. It was so heavy at 4AM I had to close the window. Sure hope the NW wind stirs things up and clears the air! Chris in Westwood.